A solenoid valve (electromagnetic valve) for controlling line pressure for shift control and clutch pressure at the time of shifting is used in an automatic transmission. The solenoid valve is attached to a control body with a built-in hydraulic control circuit provided in the automatic transmission. Conventional methods for attaching the solenoid valve to the control body are available such as fixing of the solenoid valve with a fixing piece (bracket) in comb tooth shape (so-called guillotine form) as disclosed in Patent Document 1, and fixing of the solenoid valve with a pin inserted in the solenoid valve as disclosed in Patent Document 2. On one hand, the method of fixing using the fixing piece in comb tooth shape is to fit a lateral square U-shaped concave portion formed to the fixing piece into a slit-shaped cut-in groove arranged on three surfaces of an outer periphery of the solenoid valve. On the other hand, the method of fixing using the pin is to align a linear insertion groove provided on one surface of the outer periphery of the solenoid valve and an insertion hole of the control body of the solenoid valve, and then fix the pin inserted in the insertion groove to the insertion hole of the body.
The method of fixing using the fixing piece in comb tooth shape, as disclosed in Patent Document 1, needs alignment between the cut-in groove of the solenoid valve and the concave portion of the fixing piece (so as to face each other) at the time of installing the fixing piece. This alignment is performed by rotating the solenoid valve inserted in a mounting hole of the control body. Also in this case, when a plurality of the solenoid valves are attached using one fixing piece, the alignment of all the solenoid valves need to be performed at one time. Thus, the attachment of the solenoid valves requires much time and trouble. In particular, a larger number of the solenoid valves to be attached using one fixing piece complicates the above-described alignment operation, requiring more trouble and time for assembly thereof.
The method of fixing the solenoid valve using the pin, as disclosed in Patent Document 2, needs a pin corresponding to each of the solenoid valves, a stay for retaining each of the pins and a volt for fixing each of the stays for attaching the plurality of the solenoid valves. This requires a large parts count for the attachment structure and thus complicates the structure. This also requires many man-hours for attaching the solenoid valves such as an operation to insert the pin in each of the solenoid valves, an operation to set the retaining stay for the pin and a bolting operation. This further requires many steps of part machining such as surface machining of the volt and machining of a bolt-hole (tap) and a pin hole.
Moreover, as a problem common to the above-described methods of fixing using the pin and fixing using the fixing piece in comb tooth shape, a volt is needed for exclusive use for fixing and retaining of the parts, resulting in increase in parts count. In addition, there is another problem of increase in process of part machining including volt hole drilling and boss part machining.